Prediction of radiated EMI from a d.c. bus in digital equipment using software simulation technique-a case study

Abstract

In this paper, near field and far field radiation patterns from a d.c. distribution bus on a printed circuit board containing a high speed switching device (1 GHz) are studied using finite element based solvers. First the geometric model of the PCB is drawn and material properties are assigned. Then the source and boundary conditions are defined. The simulation software uses the finite element method to solve the full, unsimplified Maxwell's equation in the frequency domain. It computes the three dimensional electromagnetic fields as a function of frequency within and around the radiating structures, the far field radiation and the S-parameters are computed and plots of fields are viewed. The results obtained using simulation technique are given graphically. The value of the fields obtained from this method is compared with the value obtained from direct mathematical calculations.